1. Field of the Invention
The invention relates to a holding device for electrolytic capacitors to enable a mechanically and electrically improved and more reliable assembly in a device. The capacitors are described; however the protection of claim 1 extends to the holder as such, even without capacitors. Provision is made for air-cooled frequency converters and servos as devices. They are used in electrical drive engineering.
To lengthen the durability of electrolytic capacitors and to be able to use the electrolytic capacitors as highly as possible, it is necessary to keep the core temperature of the electrolytic capacitors as low as possible. For high-protective air-cooled devices (IP54 and above), it lends itself to mount these electrolytic capacitors in the air flow of the cooling body. For this purpose, the following functions must be fulfilled at the same time.                Tightness between air cooling circuit (IP54 and above) and electronic compartment (IP20).        Mechanical fastening of the electrolytic capacitors so that the electric connections of the electrolytic capacitors are not damaged, even in response to vibrations.        Accommodation and equalization of very high can tolerances of electrolytic capacitors.        Optimization of the heat transfer between the interior of the electrolytic capacitors and the passed can surface.        Prepositioning of the electrolytic capacitor connections on the printed circuit board or on the busbar. At the same time, an inverse-polarity protection is to be possible.        Maintaining a predetermined screw direction (from the top) during assembly of the electrolytic capacitor component into the frequency converter or servo.        
2. State of the Art
Various solutions already exist for the fastening and the protection of capacitors in this application. EP-A 1 132 930 (Vacon Qy) describes one of these solutions. This solution, however, only serves for the protection and the fastening of the capacitors, without fulfilling demands on a direct cooling of the capacitor housing can in the air flow and a mechanical support of each of the capacitors in the proximity of the center of gravity, because the capacitors are only encased with a closed jacket without additional support. They are installed and wedged into an intermediate housing, see column 5, lines 20 to 30 and column 6, paragraph [027] therein.
Heat dissipation must occur thereby via an additional air and insulation material section. The air gap between encased capacitor and protective cover must potentially still be filled with a very expensive heat conducting paste, so as to be able to dissipate the temperatures created in the capacitor at all. In addition, an outer diameter as well as a length even of “equally large” encased capacitors is subject to very high tolerances, thus making it possible for the air gap for the heat transfer to become very large.
Under the influence of vibrations, as they can arise in response to various applications, a mechanical stabilization of the capacitor is impossible. Due to the large mass and the one-sided attachment of this capacitor type via the connector sockets on the electronic board, the contact surfaces and the support material are highly stressed, which can lead to contact problems or to the breaking of conductor tracks. Furthermore, this solution of the state of the art requires an independent protective can for each capacitor length.